Increased blood pressure or Hypertension is a highly common and often considered as dangerous condition. According to the American Heart Association one out of every three Americans over the age of 20 have high blood pressure, while many of them might not even know that. Additional blood pressure variations are often associated with various medical issues relating to heart diseases, trauma and injuries, etc. Typically, monitoring of blood pressure is considered to be one of the main parameters to be monitored for every patient. To this end it is a common practice in various medical facilities to measure patients' blood pressure periodically. Such measurement generally utilize application of certain pressure on a patient's arm or other limbs and monitoring its effect on blood flow. Although effective a common, this technique is both time consuming and cause discomfort to the patient during and between measurements.
Various techniques for optically monitoring parameters of an object, especially biological objects, including human body, are known. Some such techniques are based on monitoring temporal correlations between speckle patterns formed by reflection/scattering of coherent light from a monitored sample or tissue. For example:
U.S. Pat. No. 8,638,991 presents a method for imaging an object. The method comprises imaging a coherent speckle pattern propagating from an object, using an imaging system being focused on a plane displaced from the object.
US 2013/0144137 and US 2014/0148658 present a system and method for use in monitoring one or more conditions of a subject's body. The system includes a control unit which includes an input port for receiving image data, a memory utility, and a processor utility. The image data is indicative of data measured by a pixel detector array and is in the form of a sequence of speckle patterns generated by a portion of the subject's body in response to illumination thereof by coherent light according to a certain sampling time pattern. The memory utility stores one or more predetermined models, the model comprising data indicative of a relation between one or more measurable parameters and one or more conditions of the subject's body. The processor utility is configured and operable for processing the image data to determine one or more corresponding body conditions; and generating output data indicative of the corresponding body conditions.
General Description
There is a need in the art for novel techniques enabling monitoring of biological parameters. The present invention provides a technique enabling remote, optically obtained, measurement of circulation pressure data. More specifically, the technique enables detection of blood pressure of a user/patient while eliminating, or at least significantly reducing, a need to apply external pressure of the user or any part of the user's body.
The technique of the invention is based on determining blood pulse-wave velocity by providing heart rate measurements at two spatially separated locations on the user's body. Utilizing the obtained pulse-wave velocity data, e.g. in accordance with pre-provided calibration data, and determining data about blood pressure of the user. Accordingly, the present technique enables determining blood pressure parameters continuously and remotely, while eliminating, or at least significantly reducing, a need to apply physical pressure on the user.
Generally, the technique of the present invention may utilize speckle-based monitoring technique for determining heart rate data of the patient. The heart rate measurements may thus be obtained or provided by collecting a plurality of image data pieces indicative of secondary speckle patterns from at least first and second monitoring regions on the user's body. The collected image data pieces may be processed for determining heart rate data streams as detected in the at least first and second monitoring regions, and the pulse-wave velocity can be determined based on correlation between heart rate data streams.
More specifically, the speckle-based monitoring technique utilizes determining time-varying correlation functions between consecutive speckle patterns for determining data on vibrations of the regions being inspected. Such vibrations, typically filtered to selected frequency range, provide data indicative of heart activity and/or heart rate of the user.
The heart rate data streams from at least the first and second monitoring regions is processed using data about distance between the monitoring regions. The processing generally comprises determining correlation between heart rate measures from the different monitoring regions, also associated as phase variations between the heart rate data streams. The time variations between the different heart rate data streams enable to determine data about pulse wave velocity of blood, which is typically associated with blood pressure. The technique may further utilizes pre-sorted calibration data for determining blood pressure data in accordance with the pulse-wave velocity data.
The at least first and second monitoring regions are generally selected to be along certain path of blood flow in the patient's body. More specifically, the first region may be located on a limb (e.g. arm or leg) at a proximal position (closer to the heart) and the second region may be on the same limb but at a distal position (further from the heart. The regions may be separated by one or more millimeters or more between them, the regions may be separated by a few millimeters to a few centimeters between them. It should be noted that the at least first and second (and generally additional regions if used) may be defined by corresponding illumination spots on body of the patient. Each monitoring region may be associated with at least a portion of an illumination spot, where locations of the illumination spots are determined by directing two or more coherent illumination beams toward the selected monitoring region. Alternatively or additionally, selection of the different monitoring regions may be determined by field of view of corresponding collection units. This enables monitoring data using a large illumination region and collection of speckle patterns data from at least first and second portions of the single inspection region, i.e. proximal and distal portions of the same region.
In some configurations of the invention, the present technique may utilized sequence of image data piece collected from one or more regions of the subject's body. The processing comprises determining two partially overlapping heart rate signals associated with blood flowing through arteries and return flow through the veins. The two partially overlapping signals may be detected from a single monitoring region. The arterial and vein related heart rate data may be processed as heart rate data collected from two different monitoring regions for determining circulation data, e.g. blood pressure, of the subject.
Thus, according to a broad aspect, the present invention provides a system for use in monitoring blood circulation data of a user, the system comprising a monitoring unit comprising at least one light source unit configured for providing and directing coherent illumination onto at least one selected inspection region on the user's body, and a collection unit configured for collecting light returning for at least a portion of the inspection region and generating a plurality of image data pieces associated with secondary speckle patterns in the collected light returning from said regions; and a control unit configured and operable for receiving said plurality of image data pieces, determining correlation functions between speckle patterns in consecutive image data pieces, processing said correlation functions for determining data indicative of at least two heart rate data sequence indicative of heart rate of the user, and determining data indicative of circulation pressure of the user in accordance with said data indicative of heart rate of the user measured at said first and second monitoring regions.
According to some embodiments, the at least two heart rate data sequence may comprise arterial flow pulse beats and vein flow pulse beats collected from a common inspection region.
According to some other embodiments, the collection unit may be configured for collecting at least two sequences of image data pieces associated with corresponding at least two portions of the at least one selected inspection region.
The at least one light source unit may be configured for illuminating two or more illumination spots associated with said at least two portions of the inspection region, thereby forming at least two monitoring positions.
The at least two portions of the inspection region may comprise at least one proximal position and at least one distal position.
The at least two portions of the inspection region may comprise at least one measurement position on chest of the user and at least one measurement position on limb of the user.
According to some embodiments, the at least two portions of the inspection region may comprise at least one proximal measurement position on a limb of the user and at least one distal measurement position on said limb of the user.
According to some embodiments, the control unit may be configured and operable for determining pulse transit time in accordance with time difference between peaks of heart rate data determined from said at least two portions of the inspection region, and for determining blood pressure data in accordance with at least said pulse transit time and heart rate data.
According to one other broad aspect, the present invention provides a system for use in monitoring blood circulation data of a user, the system comprises at least first and second monitoring units and a control unit; the at least first and second monitoring units include corresponding light source units configured for providing and directing coherent illumination onto first and second monitoring regions on a user's body respectively, and detection units configured for collecting light returning from said first and second monitoring regions and generating corresponding pluralities of image data pieces associated with secondary speckle patterns in the collected light; the control unit is configured and operable for receiving said first and second pluralities of image data pieces, determining correlation functions between speckle patterns in consecutive image data pieces, processing said correlation functions for determining data indicative of heart rate of the user measured at said first and second monitoring regions, and determining data indicative of circulation pressure of the user in accordance with said data indicative of heart rate of the user measured at said first and second monitoring regions.
According to some embodiments, the control unit may be configured and operable for determining pulse transit time associated with time difference between heart rate activity data detected at said first and second monitoring regions, and for utilizing said pulse transit time for determining said data indicative of circulation pressure.
According to some embodiments, determining the data indicative of circulation pressure of the user may comprise determining data about pulse wave velocity in accordance with said data indicative of heart rate of the user measured at said first and second monitoring regions and utilizing pre-stored calibration data for determining said circulation pressure of the user.
According to some embodiments, the data about circulation pressure of the user comprises blood pulse pressure data.
According to yet another broad aspect, the present invention provides a system for use in monitoring blood pressure of a subject, the system comprises at least one monitoring unit and a control unit; the monitoring unit comprises light source unit configured for providing and directing coherent illumination onto at least one monitoring region on a subject's body, and at least one detection unit configured for collecting light returning from said first and second monitoring regions and generating corresponding pluralities of image data pieces associated with secondary speckle patterns in the collected light; the control unit is configured and operable for receiving a plurality of image data pieces, determining correlation functions between speckle patterns in consecutive image data pieces, processing said correlation functions for determining data indicative of heart rate of the user measured at said monitoring region, and determining data indicative of circulation pressure of the user in accordance with at least one pulse structure parameters of said heart rate.
According to some embodiments, the pulse structure parameters comprise at least one parameter selected from: width, height, and the time intervals between peaks forming heart pulse beats.